Organic polysulfides and particularly dialkyl polysulfides such as tri-, tetra-, and penta-sulfides have been found useful for many purposes such as additives for elastomers, antioxidants for lubricating oils, intermediates for the production of organic chemicals, insecticides, germicides and as an additive to diesel fuels to improve the octane number and ignition qualities of these fuels. These polysulfides have also been found useful in the compounding of extreme pressure lubricants and in the acceleration of rubber treating processes. Because of the high sulfur content, organic polysulfide compounds are also useful in presulfiding catalysts used in refinery processes.
Such organic polysulfide compounds can be prepared by reacting mercaptans with elemental sulfur in the presence of a basic catalyst. For example, Biensan et al (U.S. Pat. No. 3,308,166) discloses that organic polysulfides can be prepared from a mercaptan and sulfur catalyzed by an amine using an alcohol promoter.
A conventional process for producing an organic polysulfide compound such as di-t-dodecyl polysulfide is to react a mercaptan such as t-dodecylmercaptan with elemental sulfur in the presence of triethylamine as catalyst. However, the organic polysulfide thus prepared is associated with some unreacted mercaptans and residual H.sub.2 S contributing to a very unpleasant odor. Additionally, possibly because of the unreacted mercaptans and the amine catalyst, the product always becomes very unstable, i.e., the product turns cloudy, probably due to degradation of the organic polysulfide causing precipitation of sulfur. The instability along with the unpleasant odor greatly reduce the desirability and utility of the organic polysulfide.
There is therefore a need to substantially reduce the odor associated with an organic polysulfide compound. Kamii et al (Japanese Application 58-140,063) discloses a process for deodorizing dialkyl polysulfides by contacting a polysulfide-bearing fluid with 1,2-epoxy compounds. The 1,2-epoxy compounds apparently react directly with the unreacted mercaptan and hydrogen sulfide, thereby producing a product with reduced odor. Excess 1,2-epoxy compounds are reportedly removed by conventional methods, such as vacuum distillation.
However, the process disclosed in Kamii et al requires vigorous and extensive chemical reaction. Additionally, the process disclosed in Kamii et al produces a product that still has such a high mercaptan sulfur level that it would contribute to the instability of the organic polysulfide product. Furthermore, even after vigorous chemical treatment, the unpleasant odor, through reduced, still is associated with the treated organic polysulfide.
It would therefore be a significant contribution to the art to develop a organic polysulfide composition whose unpleasant odor is substantially masked or reduced and a process for the deodorization or masking of an organic polysulfide so that the organic polysulfide is made more useful for industrial uses.